Lift-bridge.



' Patented Dec. 3|, |90l. E. D. CUMMINGS.

LIFT BRIDGE.

(Application led Nov. 13, 1900.)

(No Model.) 2 Sheets-Sheet I.

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No. 689,856. Patented Dec. 3|, |901.

E. D.CUMMING-S. LIFT BRIDGE.

(Appxicacion med Nov. 1a, 1900.5 (No Model.) Y 2 Sheets-Sheet 2.

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UNITE@ STATES PATENT Ormea ELMORE D. CUMMINGS, OF ST. PAUL, MI l\ll\ll SO'lA.`

LIFT-BRIDGE.

SPECIFICATION forming part of Letters Patent No. 689,856, dated December 31,1190-1'.

l Application tiled November 13, 1900. Serial No. 36,334. (No model.)

provide a bridge of the class described iny which each span may be easily and cenvenientlyrotated from ar horizontal to a yvertical position and be held in balance by a counter- Weightv rotatably mounted in such way that its lever-arm changes atthe same rate as the lever-arm of the center of gravity of the span and in which the counterweight and all parts of the mechanism for accomplishing-these results maybe arranged above theroadway,and,

second, to provideimproved means lfor coupling the adjacent or meeting ends of the span when -mere than one span isvused, so as toprevent any movement of the ends ofthev spans relatively to each other, and' also to provide means for preventingthevtrusses from sagging atthel point of junction when under stress from moving loadspassingover thev bridge. i

To this end my features of construction, combination,l and arrangement o't partsy hereinafter `described.V

and claimed.

In the accompanying drawings, forming part of Athis specitication, Figure l is a side elevation of one spanyentire and part of the other ,span ofv a'double-span bridge embodying my invention, the spans being represented in lowered or closed position. Fig. 2 is a plan vView oflthe same, .omitting for the sake of clearness'the framework ot'. the tower.

3 is a side elevation of one span in raised or Fig.

open position, and Fig. 4 is an end'elevation ot' the same looking toward the waterway. Fig. 5 is a side elevation, with some parts broken away, of the meeting ends of the two spans of a double-span bridge, showing my devices for coupling the same and for preventing sagging. Fig. 6 is a plan of the same.'

invention consists iuthe Fig. .7 is a transverse vertical section of the same, taken on line as of Fig. 5 looking toward theleft; and Fig. 8 is a horizontal section of the same, taken on line yy of Fig. 5.

In the drawings, Arepresents the abutment .on one lside of thewaterway, upon which is Y supported a pair of suitably-braced towers B, 'positioned a distance apart alittle greater vthan the width of the bridge-span.

C represents one of the spans of the bridge,

thelowerchords 2 of which are pivoted at their outer ends by horizontal pins 3 to shoes or blocks 4, firmly secured to the towers B.

On each side of the bridge-span, nearits outer end, lis a curved member, consisting, preferably, as shown in the drawings, of a girder 5, with curved ange 6, extending from the lower-chord 2 to a point somewhat above the upper chord 7 and beyohd its outer end. Similarly curved members, consisting, preferably, of girders 8, each having a similarlycurved .flange 9, are secured by suitable radial arms lO to an axle 11, rotatably mounted in bearings l2 upon the upper ends of the towers B. The girders'S are arranged in the same plane, respectively, as the corresponding girders `5, and carry between their upper ends a counterweight'l. The ends of the girders 5 yat or near the lower chords of the bridge are connected with the ends of the girders 8 away from.thecounterweight by flexiblel `cables or chains 1 4, of lsuiicientstrength to carry the weight of the bridge, which lap around the tlangesof fthe bridgegirders 5 -when the bridge is down, as shown; l T hesecables are `of such lengthV that when the bridge is down the Alever-armk inFig. l.

of itscenter of gravity is at its maximum and the lever-arm of the counterweight is also at its maximum, and the counterweight is preferably of such weight and positioned at such a distance from the axle ll-that its 'inoment about its axis of rotation is exactly equal to the moment of the bridge-span; butits weight or position may obviously be varied,- so that itsmoment maybe slightly less or more than the moment of the bridge-span about itspivot,v

as may be desired. f' f i The bridge' may be raised and lowered by lany ordinary and suitable appliances. For

this purpose I have shown in the drawingsa pinion 15, engaging a rack 16 upon the under looy side of the flange 6 of the bridge-girder 5. The pinion may be supported from the tower B or in any other convenient way and is adapted to be actuated from any suitable source of power. For the sake of clearness the supporting means for the pinion and the mechanism for operating the same have been omitted from the drawings. Other means of raising and lowering the bridge will readily suggest themselves, the specific method of doing this forming no part of my invention. As the bridge is lifted its moment decreases and allows the counterweight 13 to descend, the moment of the counter-weight decreasing at the same rate, while the cables 14 wrap up on the flanges of the weight-girders 8 and unwrap from the flanges of the bridge-girders 5. The equilibrium between the counterweight and the bridge-span is thus preserved in any position of the bridge from its lowered position (shown in Fig. 1) to that of its extreme elevation.

The curved flanges of the girders 5 and 8 are preferably circular, but not necessarily so, as it might be desired to change the character of the equilibrium between span and counterweight at certain positions-for instance, the down position and the extreme elevated position-in order to attain either greater stability or greater ease in operation. Neither are they limited to any particular radius, as that of one panel length of the bridge-truss, as shown in the drawings, nor need they be of the same form as shown. It will be evident that the curved members keep constant the length ot' the lever-arms of the pull of the cables when they' are circular or concentric with their pivots or not quite constant when a curve ot' other form is used.

The drawings show a bridge in which the roadway-floor would be about the height of the floor-beams above thelower chords of the bridge. In bridges having roadway at a greater height the girders 5 and 8 might change their relative proportions tothe bridge from that shown inthe drawings. In special cases the bridge-girders 5 could be prolonged farther toward the towers B, making considerably more than a quadrant. In this case the cables 14 would take a greaterdetlection downward toward the girders 8, which should A low the roadway approach.

vthen be placed at a less elevation.

If desired, sheaves could be interposed between the bridge and the tower to guide the cables' and deflect them toward a horizontal to meet the girders 8, which would be supported on the towers at a greater distance from the bridge.

While I prefer to mount the curved members S, with their axle 11 and counterweight.

13, above the roadway approach, as shown in the drawings, yet by interposing a sufficient number of sheaves between the bridge members 5 and the counterweight members 8 it is possible to arrange the counterweight members 8 with their axle and counterweight bc- In the drawings the curved members 5 and 8 are shown arL ranged outside of the bridge-trusses; but they may, if desired, be arranged inside the trusses, or the top members of the en d panels of the truss may be made in two parts and the curved members be placed between them, so as to be directly in line with the trusses, or the curved members may be made in two parts, arranged one outside and the other inside of each truss of the bridge-span. The counterweight members S would in any case be arranged in line with the bridge members 5.

In the drawings a double-span bridge is shown; but obviously my invention may be used equally well with a single-span bridge, the farther cud ofthe span in that case resting upon the abutment on the opposite side of the waterway instead of meeting a second span.

In order firmly to lock together the meeting ends of the trusses of a double-span bridge to form one rigid truss without centra-l support, so that there shall b e no relative movement between the meeting ends of the trusses undel a live load nor sagging at the center by reason of loose coupling of the trusses, I have provided the devices shown in Figs. 5, G, 7, and 8 of the drawings.

As shown in the drawings, the span D is designed to be lowered in advance ot' span C, and its upper chords 17are provided on their under side with brackets 18, extending beyond the ends of the chords to form a stop or rest to limit the descent of the span C when it reaches a horizontal position. To lock together the upper chords ot' the spans, I have provided on each of the upperchords 7of span C a double toggle-joint E, the links 19 of which are pivoted at one end to a fixed block 20, secured to the upper chord, and at the other end to a movable horizontal pin 2l, working through a guide-block 22, also secured upon the upper chord 7. The toggle is operated by a screw 23, havinga right-hand thread on one end and a left-hand thread on the other, working through blocks Z4, which engage the toggle-links of each toggle at their point of connection, so that` the rotation of the screw in one direction opens both toggles and its rotation in the other direction closes them. Secured to the top of each upper chord 17 of the span D is a block 25, containing a tapering hole 26 to receive the end of the pin 21, which is tapered to fit the hole. By the operation of the screw the pin is forced into the hole with great power,bringing the trusses into alinementand aiordinga means of transmitting shearing stresses from one truss to the other. The joint 27 or the point where the top chord ends of the two trusses abut will receive the strain of compression which will come to it from live loads passing over the bridge.

The meeting ends of the' lower chords of spans C and D on each side of the bridge are composed of eyebars 28 and 29, respectively,

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exactly register be driven tightly enough through them to prevent excessive sag or de-l flection ot' the two bridge-spans when live It is loads come upon the closed structure. therefore necessary tohave the pin slightly smaller than the eyes, so that it can be easily inserted and `withdrawn when the eyebars are not stressed; but before any live load ycom es upon the structure the junction must be made tight. To accomplish this tightening of the bars upon the pin, I provide on.

each side of the bridge a toggle-joint F, with an upperlink 33, consisting of a pair of beams suitably braced together and a pair of lower links 34, the link 33 being pivoted at its upper end at 35 to plates 36, secured to the upper chord of span C, and the links 34 being formed with eyes at their lower ends to receive the pin 32 when it is driven in. The links 34 are keyed fast to the toggle-pin 37, which is free to rotate in the holes in the upper link 33, through which it passes. The pin 32 is slidably arranged within a cylinder 38, supported from the toggle-pin 37 by two arms 39, bored at their upper ends to receive the toggle-pin, to which they are keyed fast and which is extended for this purpose. The cylinder-arms 39 are in line with the short toggle-links 34 and act in precisely the same way. As the links 34 are also keyed fast to the toggle-pin 37, they cannot fallout of alincment with they cylinder when they are not engaged by pin 32. The cylinder 38 is both a support for the pin 32 when it iswithdrawn and a guide for the pin in inserting, the centers of the eyes in the eyebars being kept by the counterweights, hereinafter described, always in line with the axis of the cylinder. The pin 32 is of such length that its point never quite leaves the head of eyebar 28, the .bar-head being formed, if desired, with a boss or thickened part 40 in order more surely to hold the end of the pin,.and that its other end does not quite leave the cylinder when the i pin couples the eyebars. This pi n 32 has a 'longitudinal bore through the center and carries at its outer end a fixed nut 4l, through which a screw 42 passes into the hole in thepin. The other'end of the screw passes out through the closed end of the cylinder, being formed with collars 43, which engage the cylinderhead and restrain the screw from longitudinal movement. By operating the screw 42 in one or the other direction the pin 32 is driven out of the cylinder through the eyebar heads or withdrawn from them into the cylinder. This screw and the screw 23, operating the toggle-joint upon the upper chord,

der side of the eyebars.

can both be operated from the shore end of the span by suitable mechanism, such as sprocket wheel and chain, and they may also be connected with each other for simultaneous or successive action by a similar device.

The lower toggle Fis actuated by a rod 44, engaging the toggle-pin 37, and may extend to the shore end of the span and be operated therefrom. When the toggle is pushed into deflected position, as shown in Fig. 5, the eyebars on each side are assisted to rise to a level or straight4 position by a counterweight 45, working inside the post 46 and suspended from a cable 47, which passes over a sheave 48 and is attached to a bracket 49 on the un- These weights somewhat niore than balance the weight of the eyebars, so that when no force is exerted at the toggle-joint F the bars will be held at their highest position, which is determined by the keepers 50, attached to the posts 42. This position is such that a straight line drawn from center to center of the farther ends of the eyebars would pass through'the center of the pin-hole in the connecting ends, and is the position which gives the maximum freedom in inserting or withdrawing the pin. To prevent the toggle from being pulledbeyoud its position of maximum effect, the post toward which it is pulled is provided with buffer 5l.

In operation, starting with both spans elei vated, the span D will -be lowered so as to reach its down position somewhat in advance of the span C, which will seat slightly on the brackets 18. Then the pin 2l on each of the top chords of the bridge will be forced bythe screw 23 and toggle-joint E into the hole in the block 25, and the pin 32 will be forced by the screw 42 through the holes in the eyebars 28 and 29; The toggle-jointF will thenV be IOD pulled straight, forcing the eyebars down and tightening them rigidly upon the pin 32. In openingy the bridge the operation will be reversed.

In order toallow the trusses in a doublespan bridge to expand or contract under variations in temperature without disturbing the relative adjustment of the locking de-` vices in the meeting ends of the two trusses, one of the towers B, with its attached shoes 4, may be mounted upon rollers or otherwise arranged on the abutment so as to be capable of longitudinal movement thereon.

While I prefer to use toggle-joints, as shown in the drawings, for forcing the pins 2l upon the upper chords into the blocks 25 and for tightening the eyebars 2S and 29 upon. the coupling-pins 32 passing through them, it will be evident that other devices-such as screws, for instance-may be used to accomplish these results without departing from the principle of my invention.

Having now described my invention, what I claim as new, and desire to secure by Letters Patent, is-

l. Ina lift-bridge of the class described,

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the combination with'a vertically-rotatable bridge-span, of one or more curved members secured to said span near its axis of rotation, a counterweight rotatably mounted adjacent to the bridge-span upon a support independent thereof and a cable connecting the counterweight with the farther end of the curved member or members.

2. In a lift-bridge of the classdescribed, the combination, with a vertically-rotatable bridge-span, of a curved member secured to said span near its axis of rotation, and a similarly-curved member rotatably mounted upon an independent support adjacent thereto and carrying a counterweight, and a cable connecting the opposite ends of said curved members.

3. In a lift-bridge of the class described, the combination with abridge-span vertically rotatable upon pivots at one end and means to rotate the same, of a curved member secured to said span near its'pivoted end and a similarly-curved member rotatably mounted adjacent thereto and in the same vertical plane and carrying a counterweight, and a cable connecting the opposite ends of said curved members.

4. In a lift-bridge of the class described, the combination with a bridge-span pivoted at one end and means to rotate the same, of a pair of curved members secured to the sides thereof near its pivoted end, a pair of similarly curved members rotatably mounted upon a tower adjacent to the pivoted end of said span and carrying a counterweight at one end, the other end of each tower member being connected with the opposite end of the corresponding bridge member by a cable.

5. In a lift-bridge of the class described, the combination with a lifting-span rotatable upon pivots at the ends of the lower chords, of means to counterweight the same consisting of curved members secured to the sides of the span near its pivoted end, concentric with the pivot, similarly-curved members pivotally mounted on the bridge-abutment at a higher level than said bridge members and concentric with their pivots, a counterweight secured to the end of the abutment members adjacent to the bridge-span, and a cable connecting the farther ends of the abutment members with the farther ends of said bridge members of such length as to hold the counterweight in such position when the bridge is down that its lever-arm is at its maximum.

6. In a lift-bridge of the class described, the combinatiomwith a rotatable bridge-span, of circularly-curved members secured to the sides thereof near its axis of rotation, similarly-curved members rotatably mounted on an independent support at a higher level than said bridge members and in the same vertical planes and carrying a counterweight at their upper ends, and a cable connecting their lower ends with the lower ends of said bridge members, said cable being of such length as to hold the counterweight in such position when the bridge is down that its lever-arm is at its maximum.

7. In a lift-bridge of the class described, the combination, with a bridge-span rotatable upon a pivot at the ends of the lower chords, of a pair of curved members secured to the sides thereof near its pivoted end, a pair of similarly but oppositely curved members rotatably mounted on the bridge abutment in the same vertical planes as the respective bridge members, cables connecting the opposite ends of the bridge members and abutment members and arranged to wrap upon the peripheries of said members, and a connterweight secured to the abutment members near the free ends thereof, said counterweight being of such weight and so positioned that its moment about its axis of rotation bears at all times a constant relation to the moment of the center of gravity of the bridge-span.

8. In a double-span lift-bridge of the class described, the combination with two rotatable spans meeting at their inner ends when i'n lowered position, of means to lock the spans tightly together consisting of a toggle-joint pivoted at one end to one of the spans and at the opposite end to a tapered pin working in a similarly-tapered hole in the other bridgespan, whereby said pin may be thrust into said hole or retracted therefrom.

9. In a double-span lift-bridge of the class described, the combination, with the spans, of means to lock them securely together when down and prevent them from sagging at their meeting ends consisting of a tapering pin slidably arranged upon one of the spans and working longitudinally of the span, a similarly-tapered hole in the end of the other span and means to thrust the pin tightly into the hole.

10. In a double-span lift-bridge of the class described, the combination, with the spans, of means to lock them securely together when down, consisting of a block secured to one of the spans near its inner end and formed with a bore, a tapering pin Working longitiidinally therein, a block secured to the other span near its inner end and formed with a tapering bore, and means to thrust the end of the pin into said tapering bore.

11. In a double-span lift-bridge of the class described, the combination, with the bridgespans, of inner lower chord members consisting of bars suitably connected at their outer ends with the next chord members, means for detachably connecting their inner ends together and means for depressing said bars or their means of connection substantially as and for the purpose described.

l2. In a double-span lift-bridge of the class described, the combination, with the bridgespans, of inner lower chord members consisting of bars pivotally connected at their outer ends with the next chord members and having their inner ends detachably connected together and means consisting of a togglejoint pivotally connected at one end with the IOO IIO

upper chord of one of the spans and at the lower end with said bars for depressing said bars to tighten their means of connection.

13. In ay double-span lift-bridge of the class described, the combination, with the bridgespans of inner lower chord members consisting of eyebars pivotally connected at their outer ends with the adjacent chord members, and formed at their inner ends with registering eyes, a removable pin passing through said eyes to couple said bars when the spans are down and means for depressing said eyebars at their meeting ends whereby they are tightened upon said pins.v

14. In a double-span lift-bridge of the class described, the combination, with the bridgespans, of lower chord members consisting of eyebars pivotally connected at their opposite ends with the adjacent chord members and having their meeting ends overlapping and formed with registering eyes, a removable pin passing through said eyes to couple the eyebars, and means for tightening the bars upon the pin consisting otl atoggle-joint pivotally connected at one end'with the upper chord of one of said spans and at the other end with said eyebars whereby said bars may be depressed.

15. In a double-span lift-bridge ofthe class described, the combination, with lthe bridgespans, of inner lower chord members pivotally connected at their vouter ends with the next chord members and formed at their inner ends with registering eyes, a removable pin passing through said eyes to couple said inner lower chord members when the spans are down, means for holding said eyes in alinement, means for holding said pin in position to enter the eyes and means for depressing said inner lower chord members at their meeting ends to tighten them upon said 16. In a double-span lift-bridge of the class described, the combination with the bridgespans, of inner lower chord members pivotally connected at their outer ends with the next chord members and formed at their inner ends with registering eyes, a coupling-pin passing through saideyes to couple the inner lower chord members when the spans are down and capable of being withdrawn from all but the nearest of said eyes, a toggle-joint having an upper link pivotally connected at its upper end with the upper chord of the bridge, a toggle-pin rotatably connected with the lower end of said link and extending beyond the same on one side, lower links secured fast to said toggle-pin and provided with registering holes to receive said couplingpin, and a cylinder to support and guide the coupling-pin also secured fast to the extended end of said toggle-pin.

17. In a double-span lift-bridge ofthe class described, the combination, with the bridgespans, of inner lower chord members suitably connected at their outer ends with the next chord members and formed at their inner ends with registering eyes, a removable pin suitably supported in a frame arranged adjacent to said eyes and adapted to be thrust through the eyes to couple said chord members when the spans are down, said frame being so arranged as to hold the pin in position to enter the eyes, and means for depressing the chord members at their meeting ends to tighten them upon the pin.

18. In a double-span lift-bridge of the class described, the combination, with the bridgespans, of inner lower chord members pivotally connected at their outer ends with the next chord members and formedat their inner ends with registering eyes, a removable pin adapted to be passed through said eyes to couple said inner chord members when the spans are down, a frame arranged outside said lower chord members and adapted to support and guide the pin and to hold it in position to enter the eyes, and means for depressing the inner lower chord members at their meeting ends to tighten them upon the pin.

In testimony whereof I aftix my signature in presence of two witnesses.

ELMORE D. CUMMINGS.

Witnesses:

ELGIE H. EvANs, ARTHUR P. Lo'rHRoP. 

